Columbianetin alleviates lipopolysaccharides (LPS)-induced inflammation and apoptosis in chondrocyte through activation of autophagy by inhibiting serum and glucocorticoid-induced protein kinase 1 (SGK1) expression

Osteoarthritis (OA) is a degenerative disease of articular cartilage involving the entire joint tissue. Columbianetin (CBT) is a major active compound of radix angelicae pubescentis, which is used in the treatment of OA. This paper attempts to explore the role of CBT in OA. Lipopolysaccharides (LPS) was used to induce mouse chondrocytes ATDC5. The effect of CBT on cell viability in ATDC5 cells with or without LPS induction was determined by CCK-8 and LDH kits. The inflammatory response was evaluated using ELISA kits. Apoptosis in LPS-induced ATDC5 cells were examined by TUNEL staining. The expression of apoptosis and autophagy-related proteins was tested with Western blot. The relationship between CBT and serum and glucocorticoid-induced protein kinase 1 (SGK1) was examined by RT-qPCR, Western blot, and molecular docking. After SGK1 overexpression or addition of the autophagy inhibitor 3-methyladenine (3 MA), the above experiments were done again. Results revealed that CBT increased LPS-induced decrease in ATDC5 cell viability. CBT inhibited inflammation triggered by LPS, evidenced by reduced levels of TNF-α, IL-6 and IL-1β. Cell apoptosis was attenuated following CBT adding in ATDC5 cells exposed to LPS, accompanied by upregulated Bcl-2 expression and downregulated Bax and cleaved caspase 3 expression. In addition, CBT elevated Beclin1 and LC3II/LC3I expression but decreased p62 expression. Additionally, CBT inhibited SGK1 expression. However, SGK1 overexpression or 3 MA reversed the effects of CBT on LPS-induced loss of ATDC5 cell viability, inflammation, apoptosis and autophagy. Collectively, CBT could improve OA through the activation of chondrocyte autophagy by suppressing SGK1 expression.